I have intermittent MPH and Trip gauge readings. It will work OK after a while on the road. It kicks in after I hit 40-50 MPH (I guess) then it works OK. Does anyone know what may be the problem? I was told that a component of the motherboard was lose or had a cold solder. If so, how do you reach the motherboard ?

could be your speed sensor, its a little white plug that plugs into your differential. First thing would be to make sure the plug that goes into the sensor is clean and tight. If that doesn't work, you probably need to replace the sensor.